Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Radical Question

  1. Mar 21, 2006 #1
    This isn't exactly homework, it was a question we had on a test and I had no idea at all of how to do it, although I think I did good on the other questions.

    The result that it came to, I cant remember exactly what it was, looked kind of like this:

    (2 root 3 + 3 root 4) over (-5)

    My teacher wont let us have any question with a negative denominator. My question is how do you remove the negative from the bottom.

    EDIT: Sorry I couldn't figure out how to LaTeX this problem.
  2. jcsd
  3. Mar 21, 2006 #2
    Your LaTeX cannot be seen. Could you write the fraction normally?
  4. Mar 21, 2006 #3
    Sorry about that, it's fixed.
  5. Mar 21, 2006 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    You can take it outside the fraction or put it to the top. The fraction still has the same value;

    [tex]\frac{a}{-b} \equiv \frac{-a}{b} \equiv - \frac{a}{b}[/tex]

    They are all identical, but it is usually more acceptable to have the negative 'outside' the fraction as in the third example. :smile:
    Last edited: Mar 22, 2006
  6. Mar 21, 2006 #5
    Ahh makes sense to me, thanks for teh help. I definitely screwed that up. For my answetr I came out with fractional radicals under 1 :p
  7. Mar 21, 2006 #6
    Hootenanny explained it very well. But I could add a tip.

    Your fraction is:
    (2 root 3 + 3 root 4) over (-5)

    If you divide all the terms of the fraction by the same number you mantain it equal to the initial fraction.
    In this case you could divide by -1. So, we would have:

    (-2 root 3 - 3 root 4) over (5)
  8. Mar 21, 2006 #7
    Good point PPonte
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook